My new to me 2004 F150 4.6l 4x4 STX is having tons of clunking, shuddering and vibration issues from the rear end. The previous owner replaced the clutch packs twice professionally along with other rear end parts like seals and bearings. It was in a tbone accident at 4 years old so any placks or stickers on the door are gone. I am looking for what gear ratio my rear end is and I dont know how to read the rear dif tag . It says V83 3F 73 88 3J03. Any help is appreciated.

 

Looks like a 3.73.

 

I would check to see if the drive shaft is bent from the accident???? may be some of your problems!

 

Is the clunking and shuddering occurring when the truck is turning around a corner? If so, it's most likely the traction lock. Add another bottle of FM. I always use the stuff from Ford.